ops: add CI/CD pipeline, a/b rolling deploy, Gitea Actions workflow

- .gitea/workflows/deploy.yml — push-to-main triggers rolling deploy
- scripts/deploy-bluegreen.sh — a-stack then b-stack restart; Maven runs
  in Docker (no JDK needed on runner host); Caddy reload at end
- scripts/deploy-all.ps1 — emergency manual deploy from dev machine
- infra/docker-compose.yml — a/b pairs per service; wget health checks;
  Gitea service; Prometheus/Grafana/DB ports restricted to localhost
- infra/Caddyfile — dual upstreams with health-based routing
- infra/Dockerfile.* — one per service
- infra/prometheus.yml + grafana provisioning

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

infra/grafana/provisioning/dashboards/provider.yml

@@ -0,0 +1,9 @@
+apiVersion: 1
+
+providers:
+  - name: APIX
+    type: file
+    disableDeletion: true
+    updateIntervalSeconds: 30
+    options:
+      path: /etc/grafana/provisioning/dashboards